This invention relates to a method for producing semiconductor devices, and more particularly to a method for altering the surface characteristics of a substrate surface to inhibit or promote epitaxial growth by a second material on the surface.
In the formation of semiconductor devices by epitaxial growth techniques, a crystalline deposition material is caused to grow epitaxially on the surface of a crystalline substrate material. It is generally desirable to be able to form as precisely delineated a pattern of the deposition material or the surface as possible to permit maximum miniaturization of the semiconductor circuitry.
One technique which has been used to form expitaxially grown patterns has been first covering the substrate with a masking material, cutting the desired pattern through the masking material, depositing the deposition material by several possible methods, such as vapor deposition, and finally removing the masking material to leave the desired deposition pattern on the sruface. For example, in Olsen et al, U.S. Pat. No. 4,053,350, carbon masking material is used to define deposition regions on a substrate, using a first masking system to prevent deposition of the carbon in those areas in which crystal growth will be desired. The masking material must be a material upon which the deposition material will not grow, and must also be capable of being removed after the deposition process. The precision with which the deposited pattern can be delineated is limited, among other things, by the thickness of the masking material and the ability to completely remove the masking material first during the patterning step, and then in the removal step after deposition. A further problem with these masking techniques is that the removal of the masking material often results in the contamination of the surface of the deposited material, and even a very small amount of contamination of this surface can adversely affect the semiconductor device being produced.
Electron beams have been used in conjunction with various techniques to assist in forming precise patterns. In one technique the electron beam is used to induce a chemical reaction in selected areas of an organic film which is applied either directly to a substrate or to a previously applied coating on the substrate. The organic film can then act as a mask for formation of a deposition pattern by removing either the irradiated or un-irradiated areas with a specific solvent. In Gonda, U.S. Pat. No. 4,086,108, an electron beam is used in conjunction with a molecular beam in an MBE growth process. Gonda relates to a method of using an electron beam to control the doping of an MBE grown film which is uniformly deposited on the substrate.